In contrast to conventional gene therapy vectors, human artificial chromosomes
(HACs) are episomal vectors that can carry large regions of the genome containing
regulatory elements. So far, HACs have not been used as vectors in gene therapy
for treating genetic disorders. Here, we report the amelioration of the
dystrophic phenotype in the mdx mouse model of Duchenne muscular dystrophy (DMD)
using a combination of HAC-mediated gene replacement and transplantation with
blood vessel-associated stem cells (mesoangioblasts). We first genetically
corrected mesoangioblasts from dystrophic mdx mice with a HAC vector containing
the entire (2.4 Mb) human dystrophin genetic locus. Genetically corrected
mesoangioblasts engrafted robustly and gave rise to many dystrophin-positive
muscle fibers and muscle satellite cells in dystrophic mice, leading to
morphological and functional amelioration of the phenotype that lasted for up to
8 months after transplantation. Thus, HAC-mediated gene transfer shows efficacy
in a preclinical model of DMD and offers potential for future clinical
translation.